Deodorization and refining of tung oil



Patented Mar. 10, 1942 DEODORIZATION AND REFINING OF TUNG OIL Louis A.Gruenwald and Malcolm John Reider,

New York, N. Y.; said Reider assignor tosaid Gruenwald No Drawing.Application March 11, 1940,

Serial No. 323,400

Claims.

The present invention relates to the deodorization of tung oil and italso in its more broader aspects relates to the refining of other typesof oils.

Considerable difliculty has been experienced in deodorizing tung andsimilarunsaturated drying glyceride oils without disadvantageouslyaffecting their drying properties because of the expense involved andthe resultant decrease in quality of the oil.

As a general rule, these deodorization treat ments require complicatedand expensive apparatus and frequently they did not produce an oil whichhad satisfactory stability or which could be most desirably utilizedwith or without further processing in various textile procedures foreither finishing or otherwise treating textile yarns or fabrics.

It is among the objects of the present invention to provide an improvedprocess for the deodorization and refining of tung and other similardrying oils, which may be carried out by relatively inexpensiveprocedure without complicated apparatus or involved process steps, andwhich will produce a high grade deodorized oil having satisfactorystability characteristics and which will not have lost any of itsinitially desirable characteristics or qualities.

- Still further objects and advantages will appear from the moredetailed description set forth below, it being understood, however, thatthis more detailed description is given by way of illustration, sincevarious changes therein may be made by those skilled in the art withoutdeparting from the scope and spirit of the invention.

In accomplishing the above objects it has been found most satisfactoryto subject the tung oil to treatment with a compound or salt of areducing sulphur acid in which the sulphur preferably has a valence ofless than 6 and in which the sulphur acid preferably is combined witheither an alkali metal or an alkali earth metal in the form of a salt.

This sulphite treatment may desirably be followed by a treatment with arelatively heavy metal salt, such as for example a lead salt.

It has been found that the refining and deodorization of the tung oilmay be satisfactorily obtained when either of these treatments are usedalone, and it is contemplated to include within this invention thetreatment of the tung oil with sodium sulphite by itself or with a leadsalt, such as for example lead acetate, sulphate, chloride or nitrate oreven a lead salt of a reducing sulphur acid of the character abovedescribed.

Without limiting the invention, it has been found that the sulphitetreatment may be satisfactorily carried out as by the followingprocedure.

In a large vessel, such as an open pot equipped for heating the body oftung or other oil may be placed which is to be processed.

To this vessel is then added about it to 1% of sodium sulphite,preferably in the form of a dilute aqueous solution.

It has been found satisfactory for instance to employ 10% by weight of a5% aqueous solution of the sodium sulphite or acid sulphite.

The mixture of the oil with the sulphite is then heated withrapidstirring to 110 C. and after this temperature is reached, the oilis diluted with a thinner and then filtered, utilizing a filter aid.

Where the sulphite treatment is to be followed by a further treatmentwith a lead salt or compound, the addition of the thinner may beomitted, and after filtering or decantation of the oil, the oil may bedirectly subjected to the lead treatment.

As an example of a lead treatment which may be carried out in a similarsort of'an open pot equipped for heating, the oil may be placed and thenthere may be added to such oil from it to 1% of a lead compound whichmay, for example, consist of the acetate, the chloride, the sulphate,the nitrate or even the oxide.

The mixture is rapidly stirred and heated to 110 C. after which the oilmay be diluted with a thinner, such as heavy naphtha and filtered withthe aid of a vacuum and in the presence of a filter aid, such asinfusorial earth.

These two procedures, as given above, are quite inexpensive, do notrequire expensive apparatus and give a good yield of oil, which issubstantially odorless.

Although it is not certain what action takes place, it is found thatwith the sodium sulphite treatment there apparently is a removal ofaldehyde and ketone compounds. Although the same result is obtained evenwhere solid sodium sulphite or a solution of sodium sulphite is added inthe cold, nevertheless it has been found most satisfactory to heat thesulphite in the oil up to between to C., and preferably between 90 andC.

It is found most desirable to have the sulphite present in sufiicientamounts so that sulphur dioxide will be evolved during the heatingoperation, such evolution of sulphur dioxide apparently improving thecolor and causing bleaching of the oil, as well as removing some of theodor.

The steaming of the oil during the heating procedure from the smallamount of water present in-an aqueous solution of the sodium sulphitealso appears to be quite advantageous.

In connection with the treatment of the oil with a solid or morepreferably an aqueous solution of a heavy metal salt, such as leadacetate, it again is found most satisfactory to have an evolution ofsteam during the treating procedure and preferably while the temperatureof the mixture is being elevated to between 80 to 180 C., and preferablybetween 90 and 150 C.

The evolution of the steam in the presence of the lead salt appears tobe particularly satisfactory, in that unpleasant smelling substances,which are responsible for the odor, are apparently readily removed andit also appears that the free fatty acids not only are largelyeliminated by this heavy treatment, but also .the tendency for furtherformation thereof is greatly reduced.

The lead and similar heavy metal salts also appear to body the oil atthe same time .as the deodorization takes place, depending upon thelength of time the treatment is continued and the-temperature of thetreatment.

The lead or other heavy metal salts, and to a lesser degreathe sulphitetreatment, also appear :to precipitate or remove albuminous andproteinlike substances which are found in natural oils and which arefound to be responsible for many of their objectionable characteristics;

Although tung oil is preferred, it has been found that other paint orsaturated or unsaturated glyceride oils may also be deodorized by eitherstep .or both steps of the present invention.

.Among the oils which maybe suitably processed are China-wood oil, soyabean oil, linseed oil, sunflower seed oil, rice bran oil, olive oil,cotton seed oil, neats-foot oil and various other fish, animal andvegetable oils.

Although both the lead salt and alkaline sulphite should be in watersoluble form so that they may be emulsified in small quantities throughthe body of the oil, while the oil is being heated, insoluble compoundsmay also be employed.

The preferred lead compounds are, however, the .lead acetate, formateorother organic acid salts and less preferably inorganic acid salts, suchas lead nitrate.

Among the other heavy metals which may be used in place of or in lieu ofthe lead are iron,

mercury, cobalt, zinc, nickel, tungsten and tin. The alkali metalsulphites or bi-sulphites are usually most preferred because they areWater soluble, although the less water soluble calcium sulphite orbi-sulphite may also be utilized.

It is also less preferable to use the thio-sulphates, hydro-sulphites,.polythionates as well as other salts of reducing sulphur acids,preferably, however, excluding the sulphide.

-As many changes could be made in the features and details, and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description shall be interpreted as illustrativeand not in a limiting sense.

What is claimed is:

1. A process of deodorizing tung oil which comprises heating the tungoil first with a small quantity of an aqueous solution of a sodiumsulphite dispersed throughout the body thereof and then with a smallquantity of an aqucoussolution of :lead :acetate.

2. A process of deodorizing tung oil which Comprising heating the tungoil first with a small quantity of an aqueous solution of :a sodiumsulphite dispersed throughout the body thereof and then with a smallquantity of an aqueous solution of lead acetate at an elevatedtemperature between '75 and 180 C.

3. A process for deodorizing tun'g oil which comprises heating the tungoil first with a small quantity of an aqueous-solution of a sodiumsulphite dispersed throughout'the body thereof and then with a smallquantity of an aqueous solution of lead acetate at an elevatedtemperature between and 150 C. with agitation.

4. A process of deodorizing a tung oil which comprises mixing in thetung oil about 10% by weight of a 5% aqueous solution of sodiumsulphite, heatingwith rapid stirring to 0., diluting the oil withnaphtha and then filtering with infusorial earth.

5. A- process of deodorizingtungoil which comprises emulsifying into theoil about 20% by weight of a 3% solution of lead acetate, heating themixture with rapid stirring'to 110 C., diluting with heavy naphtha as athinner and then filtering with'the aid of vacuum and infusorial earth.

LOUIS A. GRUENW-ALD. MALCOLM JOHN REIDER.

